The need to conserve energy is constantly growing. Driven by the rising cost of energy, environmental considerations and governmental regulation, energy-consuming devices and their circuits are increasingly becoming the focus of energy controls. Traditionally, energy management programs focused primarily on lighting loads within a particular space, for example, coupling the activation of the lighting device(s) to the occupancy status of the space. As a result, the majority of lighting circuits became controlled to minimize wasted energy consumption and the focus then turned to plug loads—devices connected to the electrical infrastructure through the traditional wall outlet. This includes all devices that are left “ON”, e.g., those devices that draw electrical current, when the space is unoccupied.
Devices such as computer monitors, phone and laptop chargers, and task lighting, to name a few, draw a constant level of power regardless of whether anyone is in the room. Even when in standby mode the constant power draw of many of these devices is a measurable percentage of the overall premise energy consumption, particularly when the space is unoccupied, and the lights are “OFF”. These so-called plug loads have been recognized as a substantial energy-consuming group of devices. They are the subject of regulation and efficiency efforts that require plug loads to be turned off through occupancy or timer-based systems.
One exemplary standard that is driving the implementation of plug load controls is ASHRAE 90.1, which requires that 50% of receptacles in commercial (e.g., office) installations be controlled to limit power consumption to an acceptable, i.e., efficient, level. This standard is often referenced by environmental programs, such as LEED, which stands for Leadership in Energy & Environmental Design, and is also referenced by local codes as the standard for electrical installation efficiency. LEED is a green building certification program that recognizes best-in-class building strategies and practices. To receive LEED certification, building projects must first satisfy prerequisites and then earn points to achieve different levels of certification.
There are some known solutions that were developed to address the need to control plug loads such as those identified above. These known solutions typically take on one of three forms, Power Packs, Relay Panels (Automated Breakers) and Controlled Receptacles. Thus, the basic concept of a controlled receptacle has been known in the industry. However, the receptacle solutions currently available are all end-unit controlled receptacles. Furthermore, these units are limited in the amount of switchable current they control.
Switching, or controlled, receptacles currently on the market are typically limited in the amount of electrical current they are capable of switching. In some cases, the relay is rated well short of the maximum load currents specified for the various outlet types (e.g., 12 A from a 15 A receptacle, or 16 A from a 20 A receptacle).
Additionally, due in part to the above-mentioned electrical current limits, and partly due to space requirements, currently available controlled receptacles are typically limited to control of the individual receptacle and its built-in outlets. This can vary between switching both plugs of an outlet or just one of the two outlets of a typical duplex receptacle. In all cases, however, there is no controlled output circuit to further control additional outlets or receptacles “downstream” from the controlled device. As a result, these types of controlled receptacles require a separate device at each controlled point.